diff options
Diffstat (limited to 'lib/loopdev.c')
| -rw-r--r-- | lib/loopdev.c | 165 |
1 files changed, 119 insertions, 46 deletions
diff --git a/lib/loopdev.c b/lib/loopdev.c index dd9ead3..c72fb2c 100644 --- a/lib/loopdev.c +++ b/lib/loopdev.c @@ -116,7 +116,9 @@ int loopcxt_set_device(struct loopdev_cxt *lc, const char *device) DBG(CXT, ul_debugobj(lc, "closing old open fd")); } lc->fd = -1; - lc->mode = 0; + lc->is_lost = 0; + lc->devno = 0; + lc->mode = O_RDONLY; lc->blocksize = 0; lc->has_info = 0; lc->info_failed = 0; @@ -153,6 +155,28 @@ int loopcxt_has_device(struct loopdev_cxt *lc) return lc && *lc->device; } +dev_t loopcxt_get_devno(struct loopdev_cxt *lc) +{ + if (!lc || !loopcxt_has_device(lc)) + return 0; + if (!lc->devno) + lc->devno = sysfs_devname_to_devno(lc->device); + return lc->devno; +} + +int loopcxt_is_lost(struct loopdev_cxt *lc) +{ + if (!lc || !loopcxt_has_device(lc)) + return 0; + if (lc->is_lost) + return 1; + + lc->is_lost = access(lc->device, F_OK) != 0 + && loopcxt_get_devno(lc) != 0; + + return lc->is_lost; +} + /* * @lc: context * @flags: LOOPDEV_FL_* flags @@ -165,12 +189,6 @@ int loopcxt_has_device(struct loopdev_cxt *lc) * * * LO_FLAGS_* are kernel flags used for LOOP_{SET,GET}_STAT64 ioctls * - * Note about LOOPDEV_FL_{RDONLY,RDWR} flags. These flags are used for open(2) - * syscall to open loop device. By default is the device open read-only. - * - * The exception is loopcxt_setup_device(), where the device is open read-write - * if LO_FLAGS_READ_ONLY flags is not set (see loopcxt_set_flags()). - * * Returns: <0 on error, 0 on success. */ int loopcxt_init(struct loopdev_cxt *lc, int flags) @@ -271,7 +289,7 @@ static struct path_cxt *loopcxt_get_sysfs(struct loopdev_cxt *lc) return NULL; if (!lc->sysfs) { - dev_t devno = sysfs_devname_to_devno(lc->device); + dev_t devno = loopcxt_get_devno(lc); if (!devno) { DBG(CXT, ul_debugobj(lc, "sysfs: failed devname to devno")); return NULL; @@ -285,28 +303,50 @@ static struct path_cxt *loopcxt_get_sysfs(struct loopdev_cxt *lc) return lc->sysfs; } -/* - * @lc: context - * - * Returns: file descriptor to the open loop device or <0 on error. The mode - * depends on LOOPDEV_FL_{RDWR,RDONLY} context flags. Default is - * read-only. - */ -int loopcxt_get_fd(struct loopdev_cxt *lc) +static int __loopcxt_get_fd(struct loopdev_cxt *lc, mode_t mode) { + int old = -1; + if (!lc || !*lc->device) return -EINVAL; + /* It's okay to return a FD with read-write permissions if someone + * asked for read-only, but you shouldn't do the opposite. + * + * (O_RDONLY is a widely usable default.) + */ + if (lc->fd >= 0 && mode == O_RDWR && lc->mode == O_RDONLY) { + DBG(CXT, ul_debugobj(lc, "closing already open device (mode mismatch)")); + old = lc->fd; + lc->fd = -1; + } + if (lc->fd < 0) { - lc->mode = lc->flags & LOOPDEV_FL_RDWR ? O_RDWR : O_RDONLY; + lc->mode = mode; lc->fd = open(lc->device, lc->mode | O_CLOEXEC); DBG(CXT, ul_debugobj(lc, "open %s [%s]: %m", lc->device, - lc->flags & LOOPDEV_FL_RDWR ? "rw" : "ro")); + mode == O_RDONLY ? "ro" : + mode == O_RDWR ? "rw" : "??")); + + if (lc->fd < 0 && old >= 0) { + /* restore original on error */ + lc->fd = old; + old = -1; + } } + + if (old >= 0) + close(old); return lc->fd; } -int loopcxt_set_fd(struct loopdev_cxt *lc, int fd, int mode) +/* default is read-only file descriptor, it's enough for all ioctls */ +int loopcxt_get_fd(struct loopdev_cxt *lc) +{ + return __loopcxt_get_fd(lc, O_RDONLY); +} + +int loopcxt_set_fd(struct loopdev_cxt *lc, int fd, mode_t mode) { if (!lc) return -EINVAL; @@ -400,13 +440,6 @@ static int loopiter_set_device(struct loopdev_cxt *lc, const char *device) !(lc->iter.flags & LOOPITER_FL_FREE)) return 0; /* caller does not care about device status */ - if (!is_loopdev(lc->device)) { - DBG(ITER, ul_debugobj(&lc->iter, "%s does not exist", lc->device)); - return -errno; - } - - DBG(ITER, ul_debugobj(&lc->iter, "%s exist", lc->device)); - used = loopcxt_get_offset(lc, NULL) == 0; if ((lc->iter.flags & LOOPITER_FL_USED) && used) @@ -479,7 +512,7 @@ static int loop_scandir(const char *dirname, int **ary, int hasprefix) arylen += 1; - tmp = realloc(*ary, arylen * sizeof(int)); + tmp = reallocarray(*ary, arylen, sizeof(int)); if (!tmp) { free(*ary); *ary = NULL; @@ -749,6 +782,26 @@ char *loopcxt_get_backing_file(struct loopdev_cxt *lc) /* * @lc: context + * + * Returns (allocated) string with loop reference. The same as backing file by + * default. + */ +char *loopcxt_get_refname(struct loopdev_cxt *lc) +{ + char *res = NULL; + struct loop_info64 *lo = loopcxt_get_info(lc); + + if (lo) { + lo->lo_file_name[LO_NAME_SIZE - 1] = '\0'; + res = strdup((char *) lo->lo_file_name); + } + + DBG(CXT, ul_debugobj(lc, "get_refname [%s]", res)); + return res; +} + +/* + * @lc: context * @offset: returns offset number for the given device * * Returns: <0 on error, 0 on success @@ -840,7 +893,7 @@ int loopcxt_get_sizelimit(struct loopdev_cxt *lc, uint64_t *size) /* * @lc: context - * @devno: returns encryption type + * @type: returns encryption type * * Cryptoloop is DEPRECATED! * @@ -865,7 +918,6 @@ int loopcxt_get_encrypt_type(struct loopdev_cxt *lc, uint32_t *type) /* * @lc: context - * @devno: returns crypt name * * Cryptoloop is DEPRECATED! * @@ -1182,6 +1234,28 @@ int loopcxt_set_flags(struct loopdev_cxt *lc, uint32_t flags) /* * @lc: context + * @refname: reference name (used to overwrite lo_file_name where is backing + * file by default) + * + * The setting is removed by loopcxt_set_device() loopcxt_next()! + * + * Returns: 0 on success, <0 on error. + */ +int loopcxt_set_refname(struct loopdev_cxt *lc, const char *refname) +{ + if (!lc) + return -EINVAL; + + memset(lc->config.info.lo_file_name, 0, sizeof(lc->config.info.lo_file_name)); + if (refname) + xstrncpy((char *)lc->config.info.lo_file_name, refname, LO_NAME_SIZE); + + DBG(CXT, ul_debugobj(lc, "set refname=%s", (char *)lc->config.info.lo_file_name)); + return 0; +} + +/* + * @lc: context * @filename: backing file path (the path will be canonicalized) * * The setting is removed by loopcxt_set_device() loopcxt_next()! @@ -1197,9 +1271,10 @@ int loopcxt_set_backing_file(struct loopdev_cxt *lc, const char *filename) if (!lc->filename) return -errno; - xstrncpy((char *)lc->config.info.lo_file_name, lc->filename, LO_NAME_SIZE); + if (!lc->config.info.lo_file_name[0]) + loopcxt_set_refname(lc, lc->filename); - DBG(CXT, ul_debugobj(lc, "set backing file=%s", lc->config.info.lo_file_name)); + DBG(CXT, ul_debugobj(lc, "set backing file=%s", lc->filename)); return 0; } @@ -1314,7 +1389,8 @@ static int loopcxt_check_size(struct loopdev_cxt *lc, int file_fd) */ int loopcxt_setup_device(struct loopdev_cxt *lc) { - int file_fd, dev_fd, mode = O_RDWR, flags = O_CLOEXEC; + int file_fd, dev_fd; + mode_t flags = O_CLOEXEC, mode = O_RDWR; int rc = -1, cnt = 0; int errsv = 0; int fallback = 0; @@ -1344,25 +1420,22 @@ int loopcxt_setup_device(struct loopdev_cxt *lc) } DBG(SETUP, ul_debugobj(lc, "backing file open: OK")); - if (lc->fd != -1 && lc->mode != mode) { - DBG(SETUP, ul_debugobj(lc, "closing already open device (mode mismatch)")); - close(lc->fd); - lc->fd = -1; - lc->mode = 0; - } - - if (mode == O_RDONLY) { - lc->flags |= LOOPDEV_FL_RDONLY; /* open() mode */ + if (mode == O_RDONLY) lc->config.info.lo_flags |= LO_FLAGS_READ_ONLY; /* kernel loopdev mode */ - } else { - lc->flags |= LOOPDEV_FL_RDWR; /* open() mode */ + else lc->config.info.lo_flags &= ~LO_FLAGS_READ_ONLY; - lc->flags &= ~LOOPDEV_FL_RDONLY; - } do { errno = 0; - dev_fd = loopcxt_get_fd(lc); + + /* For the ioctls, it's enough to use O_RDONLY, but udevd + * monitor devices by inotify, and udevd needs IN_CLOSE_WRITE + * event to trigger probing of the new device. + * + * The mode used for the device does not have to match the mode + * used for the backing file. + */ + dev_fd = __loopcxt_get_fd(lc, O_RDWR); if (dev_fd >= 0 || lc->control_ok == 0) break; if (errno != EACCES && errno != ENOENT) |